Private branch exchange system



Dec. 26,1939. E. P. G. WRIGHT Er AL 2,184 540- I PRIVATE BRANCHFXCHANGE SYSTEM Filed April 16, 1938 9 Sheets-Sheet l FIG. 3 our 76 ExrEA/s/o/v LINE CIRCUIT $.95 A/Smmrwa LEAD I I. 1 IV 717' 11 FT. JFM H RR .EJPG. WRIGHT ;f"- GCZHARTLEV A T TOR/V5 V Dec. 26, 1939.

E. P. cs. WRIGHT ET AL 2,184,540 PRIVATE BRANCH EXCHANGE SYSTEM Filed April 16, 1938 JUNCTION C/ncu/r CLL 9 Sheets-Sheet 2 .&

l l rw/ M7763 /ns4 x In 2 CA BR L D EPG. WRIGHT gf ac. HARTLEY WWW! . ATTORNEY L rc 2 8 I E 3 4 i u 7'64 3 5 E Lfi l R/NG/NG TONES CIRCUIT 76 122] 11172 121 Z? mm m M PB R AC RC lNl ENTORS: WRIGHT ec. 26, 1939. E. P. e. WRIGHT ET AL 2,134,49

PRIVATE BRANCH EXCHANGE SYSTEM Filed April 16, 1958 9 Sheets-Sheet 3 EXCHANGEL/A/E TO MAIN EXCHANGE 6V GGHARTLEV ,4 TOR/VEV E. P. G. WRIGHT ET AL PRIVATE BRANCH EXCHANGE SYSTEM Filed April 16, 1938 9 Sheets-Sheet 4 y Nl/ CX/ 5y, 4% HF [41' HI J-DII-H [in H I 826 ay/ cx/ bx/ ax/' i L k4 82/ nu/ Q K BVSZOAV NU CX BX VAX NC INVENTORS: E-PGWR/GHT GIG/M RTLEV 4 7' TORNE Y e8 393% E. P. s. WRIGHT ET AL 49% PRIVATE BRANCH EXCHANGE SYSTEPE Filed April 16, 1938 9 Sheets-Sheet 5 1 22 I222 ND PR JT so 5 ME EPGWR/GHT fff GCHARTLEV WWW 4 7' TORNE V ec. 26, 3939: E, P. e. WRIGHT ET AL 9 PRIVATE BRANCH EXCHANGE SYSTEM Filed April 16, 1938 ZZV 2177 221 m 4 mm 9 Sheets-Sheet 6 SPXC SPXT 532% /L /A I By GCZHARTLEV Dec. '2, 1939.

E. P. a. WRIGHT ET AL 2,184,540 PRIVATE BRANCH EXCHANGE SYSTEM Filed April 16, 1938 9 Sheets-Sheet 7 5.190; WR/GH 7' INVENZOVRS fies 26, 1939. g ,.W ET AL v 2,184,54Q

PRIVATE BRANCH EXCHANGE SYSTEM Filed April 16, 1938 9 Sheets-Sheet 8 m ALL BACK CIRCUIT m m 2 k 0/? Mc 0c PR 7/? 50 MM M 500 TPGWR/GHT WVEVTORS- GIQHARTLEV 'ATTOR/VEV 1939- E. P. e. WRIGHT El l. 2,184,540

PRIVATE BRANCH EXCHANGE SYSTEI Filed April 16, 1938 9 Sheets-Sheet 9 FIG. 6'

F5 (5 I LOCf Ll/V56" 3 ATTORNEY Patented Dec. 26, 1939 UNITED STATES PATENT OFFICE PRIVATE BRANCH Esmond P. G. Wright EXCHANGE SYSTEM and George C. Hartley,

London, England, assignors to Western Electric Company, Incorporated, New York, N. Y.,

a corporation of New York 6 Claims.

This invention relates to private branch telephone exchange systems in which incoming calls are normally extended by an attendant, but in which so-called night-service facilities are provided for extending incoming calls when the attendants position is unoccupied.

The object of the invention is to provide improved night-service facilities.

One feature of the invention comprises a private branch telephone exchange system so arranged that incoming calls are normally dealt with by an attendant, but are automatically switched through to an extension when the attendants position is vacant and so-called nightservice conditions are in operation, characterized in this, that while night-service conditions are in operation an incoming call causes bells or buzzers to be sounded at suitable points in the building which the exchange serves and can be answered from any extension subset.

Another feature of the invention comprises a private branch exchange characterized in this, while night-service conditions are in operation an extension is individually allocated for night service to each junction from the main exchange, and the extension individually allocated to a junction is automatically selected in response to an incoming call over said junction.

The invention will be clearly understood from the following description of an embodiment of the invention shown in the accompanying drawings in which:

Figs. 1, 1A, 2, 3, 3A, 4, 5 and 6 arranged in accordance with Fig. '7 show the applicants invention applied to an automatic branch exchange system in which night-service is provided by having incoming calls cause the operation of bells or buzzers at different points in the buildings which the exchange serves and having any extension subscriber answer the incoming call by dialing the digit 8; Figs. 1, 1A and 2 show an automatic branch exchange junction line circuit terminating in a line finder; Figs. 3, 3A and 4 show a key-sending cordless position equipment; Fig. 5 shows a call-back circuit; and Fig. 6 shows a local link circuit;

Figs. 1, 1A, 2, 3, 3A, 4, 4A, 5 and 6 arranged in accordance with Fig. '7 show the applicants invention applied to an automatic branch exchange system in which night-service is provided by having a particular extension allocated for this service to each junction; Fig. 4A shows the principal changes required for this latter type of service.

. The invention will first be described in general in connection with the Figs. 1, 1A, 2, 3, 4, 4A,

5 and 6 and later specifically in connection with the two night-service arrangements, using Fig.

4 in the first instance and Fig. 4A in the second instance. I v

The key-sending equipment comprises a digit key or press-button strip 0--l, Fig. 3A, adapted to control digit storage relay groups AXCX, and AYDY. Contacts of the storage relays mark bank yfmfil, Fig. 1, of the junction line finders via cross-connecting frame CCF. If the number of extension lines is small, a key or press-button per extension line may be provided to mark the junction line finder banks direct.

The attendants set may be provided with a speak key, SK, Fig. 1A, per junction, but a doublethrow key is preferably provided for each pair of junctions.

When a call is made from the main exchange by ringing over a junction to the private automatic branch exchange, relay RB energizes immediately to ringing return battery at the main exchange even during an initial silent period; earth, 0172, r6, RB, a6, and positive junction wire. Contacts rbl open the start circuit from the 0 level and 8 level start leads OLS, 8LS of the local links so as to busy the junction to outgoing calls.

Ringing current operates relay AC; positive wire QC, 26, AC, r03, negative wire.

Earth via acl b1'4, energizes R, which locks on its left-hand winding via r6, c122, and on its righthand winding via rc I, 0", back contacts of a relay PZ (not shown) in the ringing and tones circuit to earth.

BRnow operates and connects flicker ground via FGL, speak key SK of the attendants circuit, '4, back contact of junction test relay JT of the attendants circuit, to line lamp LL. A buzzer may also be sounded.

Contacts brl connect earth from M, to the 40 ringing and tones machine start lead MSL. Relay PZ is arranged to operate every half minute after the machine has been started to release relay R if the connection has not been completed, and if key NSK in Fig. 4 is thrown.

When the attendant throws the speak key, relay CA operates via SK, lead IX, sdZ in the attendants circuit earth. Relays S, SD in the attendants circuit operate via lead X, SK, cad. The change-over of contacts sd2 renders all other junction speak keys ineffective. CA looks over its lower winding, ca3, lead VIII, to contacts 33, 5:12, in the attendants circuit, and CB operates in parallel with CA. Z energizes via two pairs of SK contacts and ca l.

Ringing is tripped via positive junction lead, cal, lead XVIII contacts of DL, NSK, right-hand winding of coil IL, lead XIX, call, r03, negative junction lead.

The attendant enquires the wanted number; lead XVIII contacts of DL, NSK, me3, contacts SPXT of splitting key SPLK, attendants telephone set, SPXT, me2, lead XIX.

Let us assume that the wanted number is 22. The attendant sets up the number on her key set l-0. Relay AX only of the storage relay combination AXCX energizes; AX, yt, key 2, 826, M, nul, sl. AX locks via arc! in series with Y to the same earth. Y energizes and transfers the key leads from relays AXNU to the second digit storage relay set AYDY.

It will be noticed that relay Nu, the fourth relay f the first storage set is connected to keys l, I, 8, 9, U, and when operated thereby, locks direct to sl, and opens the energizing circuit for Y in series with relays AX, BX, CX, so as to prevent registration of any one of said digits which are not used as first digits in the private automatic branch exchange. NU tone .via lead NUT, nuz, and coil IL, is induced in the attendants receiver.

When a first digit is correctly registered, ST energizes via (1x3 (or bard, or 0x5), k5, 114M, 8!.

The first digit having been registered on AX, key 2 is again depressed and AY is operated and locks in series with SZ which also energizes and disconnects the key-set at $26.

Earth via stZ, k3, ql, s24, lead III, cb i, hi, and its interrupter, energizes magnet JFM of the 50-point single motion junction line-finder switch, which hunts for a marked line.

Contacts l5ll of the cross connecting frame CCF in the attendants circuit are connected to the corresponding 50 contacts in the bank of wiper 771114. The group of ten lines including the wanted party is first marked and relay Q operates when the group is found via std, ncl, 03, (m2 operated, bmZ, 00:2, contact I of CCF to the first group of lines on JF #1124, c112 to earth. 1

Operation of ql immediately stops JF and also operates 0 to 8132. ll locks via 02, stZ and changes the connection of Q from the group marking wires to the line marking wires. It is to be understood that the line marking wires are multipled over all the CCF groups.

Q releases and JFM reoperates. When the marked line in the selected group is reached Q energizes via $154, 03, aya, b 12, c1112, dyZ, that, 0172 to earth. Slow-to-operate relay K now energizes fully via 01, ql, k3, st2 and locks via 0 I 703, .9152. The opening of 705 causes ST to release slowly and the opening of k4 immediately releases the storage relays AX, AY and relays Y, SZ, Q, K, and O.

Relays CL and RR in series in the junction circuit energize via cb3, lead IV, stl, k2, during de-energization of ST.

RR locks via f3, rrfi, cb5, lead VI, lcl and CL locks; earth acl, CL, 015, battery.

Since both locking circuits for R are now opened at chi. and all, R releases.

If the speak key SK had been returned before the call was properly set up, that is, before R is released, LL would flicker until the speak key was again thrown and the call completed.

Relay H tests the condition of the wanted subscribers line by means of intermittent potential on lead TPL.

If the line is busy, H does not operate and busy fiash is connected via BFL, TM, Z95, h8, 1'4, contact of JT to LL.

If or when the subscriber is free, I-I operates and locks via M5, 0195, lead VI, st3, and LL glows steadily in a circuit via JT contacts, 14, M3, M5. The wanted party is rung, ringing source, winding of F, W3, h l, y'fmZ, wanted partys bell, y'fml, 71.2, 112, earth.

When the subscriber replies, F operates and at f3 releases RR which releases F.

When the speak key is return to normal S and SD in the attendants circuit release, and release CA and CB so that a conversational circuit is completed; junction positive wire, Tel, 0115, upper windings of D and L, .23, zi, 7'12, 712, jfml, extension loop 771122, hr, r13, .22, 24, lower windings of L and D, r03, junction negative. Relay L immediately operates and holds Z at Ll. The relays now energized are L, Z, H, CL, BR.

The attendant may find it necessary to rekey and so transfer the connection to another line in the following cases:

(1) If the called party is busy, and the calling party asks for another extension.

(2) If there is no reply to ringing and the calling party asks for another extension.

(3) If conversational connection has been set up but transfer is required, for instance, if the call is really for another party.

In all three cases assuming that the speak key is still thrown relays CA, CB, S, SD, CL, BR are energized, but the relays RR and H are differently operated in these three different conditions.

In condition 1) relay RR only is energized.

In condition (2), relays RR and H are both energized.

In condition (3), relay H alone is energized.

Whichever of these two relays RR and H are operated, operation of one of the digit keys in setting up a new number automatically releases the said relay or relays.

The depression of the digit key energizes one or more storage relays AX, BX, CX followed by relays Y and ST as before. The locking circuit for RR and H are via 13 and TTB, and via hB in common via c115, lead VI, back to st3, to ground. Operation of ST therefore opens both locking circuits and RR and/or H release.

Depression of the second digit key operates one or more storage relays AYDY and relay Z. As before JF hunts for the marked group and line in turn and the new line is tested and if idle, rung.

When the call is set up the speak key is restored, S, SD, CA, CB release. The attendants circuit is back to normal and available for dealing with another call, whie in the exchange line circuit, relays L, Z, H, CL, BR, are energized as previously stated.

When the private automatic branch exchange extension hangs up, L releases followed by Z. Clearing alternating current may be applied via lead CLL, 292, 013, YE and YF, 23 and 24 in parallel to the junction leads. When the impedance of the two parallel alternating current circuits become unbalanced due to change-over from the conversation feed circuit to the junction line circuit at the main exchange, and relay AC which is bridged across the circuit energizes, change-over of contacts acl releases relay CL but holds BR to prevent R being energized.

Release of CL breaks the clearing circuit at 012, so that AC and BR release. The opening of contacts br3 releases H and the circuit is back to normal.

If the main exchange subscriber holds the connection AC does not energize, and CL, BR, and H remain operated after L and Z are released. Lamp LL is then continuously lighted via JT contact, M, M, .25. The private automatic branch exchange attendant on observing the lamp comes in and makes enquiries.

If an extension party engaged on an incoming call from the main exchange wishes to call back to another extension while the main exchange call is held, he depresses a subset button which earths both legs of his line. Differential relay D, Fig. 1, energizes and contacts (1i cause RC to operate via lead XXVII to the call-back circuit, Fig. 5, mod to battery.

Earth via 25, Fig.1, r05, Fig. 2, lead XXV, sdE, Fig. 5, prl, lead XXVIII, lower winding of RC, Fig. 2, r08, lead XXIX, left-hand winding of MC, Fig. 5 to battery, locks RC and energizes MC.

The opening of contacts ma l, Fig. 5, prevents any other RC relays energizing.

The junction line, Fig. 2, is bridged via r02, to hold the exchangeline connection while the extension line is connected via r05, r03, via the leads XXI, XXII to the call back circuit in which the said line is connected via a differential relay DR to a spare extension line circuit SEL. While the subset button is still depressed, relay DR is energized.

When DR is released by release of the subset button, relay DC which was short-circuited via dci, dr2, now energizes; earth ml, DC, mc3, battery.

The calling extension line loop causes the spare line circuit to seize a local link which connects earth to the third wire of SEL to operate K, The extension party now dials into the local link and completes the call-back connection.

The local link is so arranged that after the second digit has been dialed, it puts a resistance earth back on the fourth wire in response to which SD operates. SD locks via sti l, to the third wire of the spare line SE L. SDD now en ergizes via $653 and the fourth wire of SEL in series with a relay in the local link which sets up a called party release condition, and locks via said-2, pri, 5015, tr3, to earth.

If the extension desires to return to the exchange oall he depresses his button again. Relay DR operates and operates relay PR via dcl, drZ. The opening of contacts pr! transfers the control of relay RC to front contact drl, so that as soon as DR releases RC will release during the slow release of PR. The release of RC will cause the local link circuit to release, and will restore the exchange line talking condition via. rcl, rc3.

If the extension wishes to transfer the call to the second extension he merely replaces his receiver. This will release the L and Z relays of the junction circuit and 25 disconnects earth from XXV thereby releasing relay K. The local link will not release in this condition since it is in the called party release condition. As a consequence of this relay SD will remain operated and when K releases relay TR will operate via sail, ki, moi in parallel with MC. TR connects earth to lead XXIII via trl, prl, sd5, trt, m2 and to lead XXIV via trill, thereby forcing the rel-ease of the exchange line circuit H relay and operating relay F. At the same time TR connects relay M in parallel with a 20% resistance to the fourth wire of the spare line circuit BEL; this is extended via the link to a fourth wiper oi the connector switch andserves to mark the called extension on the bank 971715 of the exchange line finder. JF, Fig. 1, hunts for the marked line; JFM, hl, ft2, fl. When the marked line is found relays M and FT, Fig. 1, will operate, and release RC at m2. When M operates, DC releases slowly. During release of DC, M operates MM which via mmZ, dc2, connects earth on the third wire of SEL when DC releases. M has a long release time and maintains this earth for sufficient time to force the release of the'guard relay in the local link. SD is released by the local link and the call-back circuit returns to normal. In the exchange line circuit, H reoperates via i252, fl, and locks. TR incidentally, disconnects the 8, 9, and ll level. start leads to reserve the multiple exclusively for the use of the call-back cirouit during the transfer process.

If the extension wishes to call the attendant he presses his button twice in succession. The first operation establishes the beginning of the ca1l-back condition and relays DC, MC, and K are operated. The second operation without dialing, i. 6., prior to the operation of SD extends earth via dr2, dcl, sztdd, lead XXVI, ml to relay R in the exchange line. Flicker ground is connected via FGL, SK, r4, JT contacts to flash lamp LL. At the same time PR is operated and releases the call-back circuit as previously described.

The attendants sets are not permanently at' tended, and as is usual so-called night-switching is provided. This may be provided in either of two ways according to requirements.

In one arrangement, using Fig. 4, throwing of the attendants night switching key NSK causes buzzers or bells distributed at selected points around the building served by the private automatic branch exchange to be operated when an incoming call arrives. The call can be answered from any extension.

By, dialing 8 from an extension to a local link a waiting incoming call is automatically connected to said extension and the local link released.

The call can then be transferred as above to any desired extension.

With the dial 8 facility wired up in accordance with Fig. 4 and the night service key thrown, an incoming call operates RB, AC. and BR, but R does not lock up since battery has been removed from lead XIV by NSK. Earth via 18, lead XIII, NSK, prl, lead BUL, operates the buzzers.

On reply by an extension, 2. locai link, Fig. 6 is seized and when digit 8 is received by its up and around selector FS, relay G is operated over the vertical bank VB in series with a common relay BS which connects earth to the lead BLS. As indicated on NSK, this lead is taken through normally open contacts of NSK to prevent an incoming call being taken out of the attendants hands in this way when the attendant is present.

This earth via BLS, Fig. 1, rl, br2, rbl, (since RB was released by R) operates F. J FM is operated via its interrupter, hl, ft2, fi, andJF hunts for the answering extension. When this is found FT energizes; earth, f2, FT, gifm5, ZfmB, gl, battery. Contacts ftZ stop JF, and contacts ftl short-circuit the high resistance winding of FT to cause a relay K in the local link which was held via g! to release and cause the local link to restore to normal. Relay H is energized via ft2, fl, and

' locks via hi5, 02 5, 111-3.

It will be noticed that the normal ringing trip circuit is through NSK and that this is now open.

Ringing from the main exchange is not tripped until after H operates. Relay LG now operates to the extension loop, and at Z93 bridges L on the junction line. L energizes followed by Z which cuts the connection through releasing LG. Relays AC, R, release, followed by F. BR. holds to lg i and 25 in turn and remains operated.

The alternative night service using Fig. 4A operates as follows. On an incoming call with key N SK thrown, relays RB, AC, R, and BR operate as before and R locks via r6, cb2.

Earth via 15, NS winding, lead VII, s2, Fig. 3, NSK, NC winding to battery causes NS and NC to energize, NS closes contacts alternative to the speak key make contacts so that CA, Fig. l, energizes via nsl, lead IX, sd2. Relay ME, Fig. 3A, then operates via 35, lead XI, 1153 to 00.4, and closes a circuit via me! and lead XI for operating S and SD. ME locks via me t, s6, while S and SD hold via s5. CA then locks via cs3, lead VIII, to a; and M12 in parallel and CB operates in parallel therewith. Z operates via 1282, 1283, cad and prepares a ringing trip circuit via D, L, .23 and 24, 2| and s2, and the extension line. ND operates to n05, and NS locks via n84, lead XII, NSK to n02.

NC may lock in either of two ways according to rin ing conditions. When ringing return battery is on the positive wire (as opposed to battery on the negative wire from the junction line circuit) NC locks via M03, zai, NSK, DL contacts, lead XVIII, ca'i, to the positive junction wire, so that if the call is abandoned NC immediately releases.

If. however, there is no direct current condition on the junction leads characteristic of ringing, as in the case of a manual main exchange, NC has an alternative locking circuit (not provided in the previous case) via mc3, ial, and back contact of P2 in the ringing and tones circuit in parallel to back contacts nd2, s22. As previously stated, PZ operates at half-minute intervals while the ringing and tones circuit is in use.

Inte rupted earth is now connected via lead s i, s23, nod, 4 to operate AX which looks in series with Y via k4, nul, sl. Contacts g4 now connect the same earth to AY which operates and locks in series with SZ to sl. Y and Z operate. As before ST operated via acr3, k5, nul, sl when -X energized and closed a circuit for JFM, Fig. 1 via cb i, lead III, se l, ql, k3, st2.

JF is stopped on the night line individual to the calling junction by Q; Q, 3154, ncl, lead V, nsii, contacts individual to the junction, lead II, jumper to night line, :ifm l, 0112. Operation of contacts ql cause and K to energize in turn, since change-over of contacts 03 no longer opens the circuit of Q. Contacts M and k5 release ST, AX, AY, and Y, but SZ is locked via 32!, n05.

During release of K, earth via k2, stl, lead IV, 0113, energizes RR and CL and the extension is tested by H. ST, K and 0 release but RR and H. when operated lock via cb5, lead VI and first kl and later st3. The extension is rung via F and on reply F releases RR at f3 and is then itself released.

Relay IA operates to the extension loop; battery, IA winding, meZ, SPXT, SPXC, lead XVI, cat, D and L windings, at, 22, W3, n4, y'fmZ, subset loop, y'fmi, hi5, W2, zl, 23, L and D windings ca5, lead XV, SPXC, SPXT, me3, IA winding, earth.

Contacts iai release NC which releases ND, SZ, and NS (at n02 and ndl) S and SD are released, followed by ME, CA and CB. The conversational connection is cut through and L operates, holding slow-release relay Z. Main exchange ringing is tripped, the connection is completed, and the attendants circuit is completely released.

In the case where NC locks via back contact of P2, opening of this contact while NC is energized releases NC, and the attendants circuit and junction circuit return to normal. Another burst of ringing from the main exchange will then start another connection.

The attendant is provided with a junction test key J'IK, Fig. 3A, operation of which energizes a relay JT controlling contacts associated with each junction speak key SK, Fig. 1. Closure of the JT contacts causes the lamps LL of all busy junctions to light via contacts 1W5, so that the attendant can choose an idle junction for an outgoing call. Of course back contacts of BR could'replace front contacts 1775 and the lamps of idle junctions only lighted.

What is claimed is: p

.1. In a telephone system, an exchange, incoming lines, a switch for each line, an attendants position including a control equipment, means responsive to the operation of said attendants control equipment for establishing a connection from an incoming line on which a call is waiting to a subscribers line over the associated switch, night service circuit means, switching means for disabling said attendants control equipment and enabling said night service circuit means, and means operative when a call is waiting on any incoming line and the night service circuit means is enabled for establishing a connection from said incoming line to a subscribers line over the associated switch.

2. In a telephone system, an exchange, subscribers lines, an incoming line, a switch, an attendants position including a control equipment, means responsive to the operation of the attendants control equipment for establishing a connection from the incoming line to any subscribers line over said switch, night service circuit means, switching means for disabling said attendants control equipment and enabling said night service circuit means, and means responsive to the dialing of a certain digit by the subscriber of any line when said night service circuit means is effective and a call is waiting on the incoming line for actuating said switch to connect the dialing subscribers line to the incoming line.

3. In a telephone system, an exchange, subscribers lines, an incoming line, a switch, an attendants position including a control equipment, means responsive to the operation of the attendants control equipment for establishing a connection from said incoming line to any subscribers line over said switch, night service circuit means, switching means for disabling the attendants control equipment and enabling the night service circuit means, and means respon sive to the dialing of a certain digit by the subscriber of any line when said night service circuit means is enabled and a call is waiting on said incoming line for actuating said switch to hunt for the dialing subscribers line and connect it with said incoming line.

4. In a telephone system, an exchange, subscribers lines, an incoming line, a switch, an attendants position including a control equip ment, means responsive to the operation of the attendants control equipment for establishing a connection from said incoming line to any subscribers line over said switch, night service cir cuit means, switching means for disabling the attendants control equipment and enabling the night service circuit means, means responsive to the dialing of a certain digit by the subscriber of any line when said night service circuit means is enabled and a call is waiting on said incoming line for actuating said switch to hunt for the dialing subscribers line and connect it with said incoming line, and means for releasing said lastmentioned connection between the incoming line and said subscribers line and for establishing a connection from said incoming line to another,

subscriber's line.

5. In a telephone system, an exchange, subscribers lines, switches, incoming lines each terminating in an individual switch, an attendants position including a control equipment, means responsive to the operation of the attendants control equipment for establishing a connection from a calling incoming line through the associated switch to any subscribers line, night service circuit means, switching means for disabling said attendants control equipment and enabling the night service circuit means, and means responsive to a call on any incoming line when the night service circuit means is enabled for connecting said incoming line to a particular subscribers line over the associated switch.

6. In a telephone system, an exchange, subscribers lines, switches, incoming lines each terminating in an individual switch,,an attendants position including a control equipment, means responsive to the operation of the attendants control equipment for establishing a connection from a calling incoming line through the associated switch to any subscribers line, night service circuit is enabled for actuating the corresponding relay, and means operative on the actuation of said relay for actuating the switch associated with said incoming line to connect said line with a particular subscribers line.

E'SMOND P. G. WRIGHT. GEORGE c. HARTLEY. 

